Maybe he wanted to hide the staff because 'it was too dangerous for mere mortals" XD

About the faction you would play, if it has to be one of the default factions maybe make the protagonist one of the lich lords (caror perhaps?) and make him kill drakes XD or maybe make it some variation of a dwarf campaign.

So, Delfador staff was the first mage's staff, and the Rod of Justice another thing...

About the faction: I can't use the elves, because they lived in the Great Continent, I can't use dwarves, because they lived in the Great Continent: but maybe I can use a dwarf clan in the depths of Irdya (in TRoW, Burin the lost was a underground traveler).
About trolls, nothing. They lived in the Great Continent.
Drakes are the principal enemy.
Undead will appear later in the story.
For Khalifate, I have a story planned, but not in this campaign.
Loyalists ... well, they were the "sequel" of other humans who inhabited the Old Continent, therefore, technologically advanced on that island. However, those who stayed on the old continent did not become what the loyalists are now.

What can we do? Well, another faction, like Aragwaithi, can be the primitive humans that inhabited the Old Continent.

The Great Library of WML is huge and extense. I must find the book who will lead me to create a perfect campaign.Future Project:History of Vindalf

Talking about orcs: they allied with the wesfolk when they were in the Green isle, in year 20BW. But, how the Wesfolk managed to ally with such creatures, maybe because they were old friends?

No They were allied with the Lich Lords...NOT with the Wesfolk. The Wesfolk were just followers of the Lich Lords and were later dismissed (TRoW).
The Lich Lords built a portal to the Old Continent and brought the orcs into the Green Isle.

After a long time of learning WML (and much more things, a year gives much time to read and think about Wesnoth lore ...), I feel ready to create some UMC. But, in first place, I need the ask to some questions:

—What is known about the pre-Wesnoth history in the campaigns UtBS, IftU and AtS? I mean the period of time since the creation of the new Universe (the beginning of the Second Cycle) until the founding of Wesnoth. What happenned to the Guardians, the creation of the planets, the creation of life on Irdya, the history of the elves and how was created the Ka'lian, and also wich powerful artifacts (such as the Ruby of Fire) were created in those far epochs.

—In mainline, what is known about Konrad II and the silver age of Wesnoth (the official timeline doesn't explain much about this age)?

—What happenned in Wesnoth after the silver age, I mean, the age of the Son of the Black Eye?

Thanks!

Note: Why aren't IftU and AtS mainline? They are probably the best campaigns ever made . Seriously, I want to know it .

The Great Library of WML is huge and extense. I must find the book who will lead me to create a perfect campaign.Future Project:History of Vindalf

According to the main timeline, konrad II's death was followed by a civil war. The UMC Soldier of Wesnoth takes place during this civil war, and also includes first contact between Wesnoth and the Dunefolk in the form of an invasion. The current king turns on his people (probably because of the ruby corrupting him, or because kings are like that - there's some heavy handed political rethoric in this campaign that didn't ring well with me) and gets overthrown by one of his rivals.
Note that this is still over 100 years before Black Eye (I actually have a few plans for a campaign for that timeframe). Also note that Soldier of Wesnoth ties in to the Dragon trilogy, which is not compatible story-wise with project Aethea (Genesis, IftU and AtS). It is also not compatible with the current canon worldmap, because is a part of it should be taking place where the Sleepless Sea is. In the current map, there's no direct connection between Kerlath and the Southern Wastes

Also, IftU and AtS aren't mainline because ShadowM wants to retain full rights over that storyline. At least that's what i gathered from what I've been told. If it gets mainlined, it's no longer the author's story.

What is known about the Ka'lian members shown in The Legend of Wesmere? How old are they and when they die?
Also, is the Ka'lian composed only by members of Wesmere, or are there elbes from other forests?

The Great Library of WML is huge and extense. I must find the book who will lead me to create a perfect campaign.Future Project:History of Vindalf